Langerhans cell histiocytosis (skeletal manifestations)

The skeleton is the most commonly involved organ system in Langerhans cell histiocytosis (LCH) and is by far the most common location for single-lesion LCH, often referred to as eosinophilic granuloma (EG) (the terms are used interchangeably in this article). For a general discussion of this disease please refer to the article on Langerhans cell histiocytosis (LCH).

Epidemiology

The skeletal system is the commonest site of involvement of Langerhans cell histiocytosis, and in 60-80% of cases is the only organ system involved. It primarily occurs in older children and young adults, with a male to female ratio of 2:1.

Clinical presentation

The lesions may be asymptomatic and discovered as an incidental radiographic finding.

When symptomatic, patients complain of pain, swelling and tenderness around the lesion. Systemic symptoms may also be present, including general malaise and, on occasion, fever with leukocytosis.

Pathology

There is proliferation of Langerhans cells with an abundance of eosinophils, lymphocytes and neutrophils. These cells produce prostaglandins which result in medullary bone resorption: this is what causes the symptoms.

Location/distribution

Patients may have one or, less commonly, many lesions. The most common locations are the skull and long bones 5, 6:

skull: ~50%

pelvis: 23%

femur: 17%

ribs: 8% (most common in adults)

humerus: 7%

mandible: 7%

spine

Radiographic features

Plain radiographs

Skull

solitary or multiple punched out lytic lesions without sclerotic rim

double contour or beveled edge appearance may be seen due to asymmetrical involvement of the inner and outer tables (hole within a hole) sign 7

CT

Similar to plain film findings with better demonstration of cortical erosion and soft tissue involvement. Excellent for biopsy and surgical planning.

MRI

Signal characteristics include

T1: typically low signal

T2: isointense to hyperintense

STIR: hyperintense

T1 C+ (Gd): often shows contrast enhancement

Nuclear medicine

There is a variable appearance on bone scintigraphy, with lesions showing an increased or decreased tracer uptake depending on the histological picture. Nonetheless, bone scans are helpful in other asymptomatic lesions.

Treatment and prognosis

Prognosis is excellent when disease is confined to the skeleton, especially if it is a solitary lesion, with the majority of such lesions spontaneously resolving by fibrosis within 1-2 years. However, where symptoms persist, other treatment options may be considered:

excision and curettage 3

steroid therapy: intralesional injection

chemotherapy

radiofrequency ablation 4

radiotherapy for spinal lesion

History and etymology

The term eosinophilic granuloma was coined by Lichtenstein and Jaffe in 1940 2.